Method of adding ingredients to a dishwashing medium

ABSTRACT

The active ingredients of the rinsing and washing media of a commercial dishwashing machine, which are incompatible in concentrated solutions, are independently introduced into the rinse line and washing medium respectively. The flow of the concentrated solutions of the active ingredients is responsive to a predetermined rise in the pressure of the water being added to the dishwashing medium thereby assuring that a quantity of each of the active ingredients is added each time water is added in proportion to the quantity of water added.

United @tntes ir ntent "111111111 [54] MlE'iililUUtlll UH ADIDHNG IINGREDHENTS TU A DIISHWASHHNG MlEiiMlUM [72] Inventor: John B. Tutlrilli, Kansas City, Mo.

American Dish Service of Kansas City inc, Kansas City, M0.

221 Filed: i eb.16,l1970 211 Appl.No.: 11,613

[73] Assignee:

[52] US. Cl .122/57 [51] ..B67d 5/68 {58] Wielld ollfiearch ..222/l, 57; 134/2, 25, 29, 36

[56] References Cited UNITED STATES PATENTS 1,087,958 2/1914 Leavitt ..222/57 1 Felt, 29,1972

3,369,705 2/1968 Curtis et al. ..222/57 Primary Examiner-Stanley H. Tollberg Att0rneySchmidt, Johnson, Hovey & Williams [5 7] ABSTRACT 7 Claims, 1' Drawin Fiwnre BASASAZl PATENTEDFEB29 I972 mc cmrtsom JNV/iN/UR B. Tufhill John I TTos.

MillE'lllrllUtlD i? AlDDlNG TNGTQEDHENTS TO A Dliilill/JASll-HNG MElDll L h/Il This invention relates to a method of washing dishes and, more particularly, to a method for introducing the active ingredients of the washing and rinsing media, which ingredients are incompatible in concentrated solutions, into the respective media in a liquid state.

Prior methods of mechanical dishwashing at both commercial and domestic levels have relied primarily upon powdered detergents. A major disadvantage of powdered detergents is their inability to get all of the active ingredients into solution at the same time unless the powdered detergent is added manually directly to the washing medium. This is attributable to the fact that the powdered detergent includes more than one active ingredient each of which has its own rate of solu bility making it impossible to achieve complete solvency of all of the ingredients simultaneously as originally formulated. This phenomenon, which has been described as preferential solubility is a particular problem in commercial dishwashing installations. The concentration of the washing medium in such installations is required to be maintained at all times at a certain predetermined level. This requires the periodic addition of quantities of the active ingredients of the washing medium since a single washing medium is normally utilized through a number of washing cycles and rinse water is periodically introduced into the medium during each cycle. The introduction of the rinse water dilutes the concentration of the active ingredients in the washing medium and requires the addition of further quantities of these ingredients.

Although the problem of preferential solubility is eliminated by introducing the active ingredients into the dishwashing medium in a liquid state, it has heretofore not been considered practical to do this since the washing medium is normally comprised of ingredients which are incompatible in concentrated solutions. For example, two common ingredients are an organic chelating agent and a hypochlorite salt. The hypochlorite salt attacks the organic chelating agent in a con centrated solution of the two and destroys the latter. As another example, a complex inorganic salt and an inorganic base are two common dishwashing ingredients; however, the concentrated base will cause the complex inorganic salt to precipitate from a concentrated solution. While these compounds are compatible in very dilute solutions, it is not practical to supply them to a commercial dishwashing machine in such dilute solutions because of the quantity required. it is to be understood, therefore, that the term concentrated solution" as used throughout this application refers to any solution wherein two or more ingredients are present in sufficient quantities so as to be incompatible.

Prior sensory mechanisms for commercial dishwashers previously introduced a quantity of powdered detergent into the washing medium in response to the mechanism opening a solenoid valve on an incoming hot water line, hot water flow ing through undissolved powdered detergent which has been placed in a separate vessel, not a part of this mechanism but adjacent to the machine, the overflow from this vessel then being directed to the washing medium in the machine. Such mechanisms have proved both expensive and unreliable. The present invention overcomes the problems previously associated with introducing the active ingredients of a dishwashing medium into the medium in a liquid state by providing separate concentrated solutions of those ingredients which are incompatible and independently introducing a quantity of each solution into the medium each time water is added thereto.

it is, therefore, the primary object of the present invention to provide a method of adding active ingredients to a liquid dishwashing medium whereby, though the ingredients are incompatible in concentrated solutions, they are introduced into the medium in a liquid state thereby avoiding the problem of preferential solubility that exists when the ingredients are added in powdered form.

Another object of the invention is to provide a method of adding active ingredients to a liquid dishwashing medium whereby an exact quantity of each ingredient is added each time water is introduced into the medium thereby assuring aecurate control over the concentration; of the washing medium.

As a corollary to the above object, it is an object of the invention to provide a method of introducing active ingredients into a liquid dishwashing medium whereby there is no time lapse between addition of water and addition of the active ingredients but rather the ingredients and the water are added simultaneously.

it is a further object of the invention to provide a method as described above whereby a definite quantity of each active ingredient is added to the washing medium each time water is added thereto without the need for sensing changes in the pit or concentration of the washing medium thereby eliminating the sensing mechanism previously required for this purpose.

As a corollary to the above, it is an object of the invention to provide a method as aforesaid whereby the problems of caking and corrosion of the sensory mechanism previously located in the dishwashing medium are avoided by eliminating this mechanism.

Still another object of the invention is to provide a method of washing and rinsing dishes whereby the incompatible ingredients in the washing and rinsing solutions are independently introduced into the washing medium and the rinse line, respectively, each time a quantity of water is introduced into the dishwashing machine.

In the drawing:

The single FTGURE is a schematic illustration of apparatus for carrying out the method of the present invention.

Referring to the drawing, a commercial dishwashing machine is designated generally by the numeral llll and includes a housing T2, the lower part of which defines a tank for the dishwashing medium M. The level of the medium i l in the tank is illustrated by the broken line which extends transversely between the end walls of the machine lit. The washing medium is maintained at the level indicated by an overflow drain 116. A pair of dishwashing racks ll} are illustrated resting on a support 20, it being understood of course, that conven tional conveyor mechanism would normally move the racks along the support Zll. A first pair of wash manifolds 22 are disposed beneath the support 20 and a second pair of wash manifolds 24 are disposed from above the support 20. Conventional pumping apparatus (not shown) removes the washing media i l from the tank at the bottom of the housing l2 and distributes it under pressure through the wash manifolds 22 and 24.

Water is supplied to the machine ll ll through a conduit 26 which is provided with a shutoff valve 2%. The conduit 26 is teed to present a rinse line 30 for delivery of rinse water to a pair of upper and lower rinse manifolds 32 and 32a. The rinse line 30 is provided with a shutoff valve: 34 which is controlled by a solenoid 36 or other appropriate means coupled with the timing mechanism (not shown) of the machine iii. A pressure regulator 38 is also provided in the line Ell.

Solution 1 represents one of the ingredients of the washing medium M and is preferably comprised of concentrated sodium hydroxide, a 5.5 percent by weight solution of sodium hypochlorite, and water, each in equal proportions by volume. Solution 2 represents the other of the ingredients of the washing medium Ml and is preferably comprised of 27%pounds of sodium tripolyphosphate, 47 pounds of sodium 5.5 6%pounds of sodium hydroxide flakes, with the foregoing three com pounds dissolved in sufficient water to yield 30 gallons of solution. Solution 3 represents a rinse additive which preferably includes 7%gallons of an ethyloxylated fatty alcohol or polyethyloxylated fatty alcohol, 1 gallon of sodium xylenesulfonate 40 percent by weight, and l /hgallons of isopropyl alcohol, with the foregoing three compounds being dissolved in sufficient water to yield 30 gallons of rinsing solution. The rinse additive forms a monomolecular" filrn on the rinsed tableware thereby preventing droplets of water from adhering thereto and thus avoiding water spotting. Solution No. l is introduced into the washing medium lid by a first pump ill which is preferably of the so-called squeegee type," a term readily familiar to those skilled in the dishwashing art. The pump 40 delivers solution one to the tank at the bottom of the dishwashing machine through an appropriate conduit 42 which extends through the housing 12 at a point below the wash rack support 20. Solution No. 2 is delivered to the washing medium 14 through an appropriate conduit 44 by a second pump which is also preferably of the squeegee type. Solution 3, which is the rinse additive, is introduced into the rinse line 30 through an appropriate conduit 48 by a third pump 50, also preferably of the squeegee type.

Each of the pumps 40, 46 and 50 is controlled by a pressureresponsive switch 52, the latter being electrically coupled with each of the aforementioned pumps. A pressure tapline 54 connects the switch 52 with the rinse line 30 through a first arm 56 and with the inlet conduit 26 through a second arm 58. A first check valve 60, of the imperfect seating type, is disposed in the first arm 56 and a second check valve 62, which is also of the imperfect seating type is disposed in the second arm 58 for purposes to be made clear hereinafter.

Since, as previously mentioned, the concentrated sodium hydroxide in solution number one would cause the sodium tripolyphosphate and sodium hexaphosphate in solution No. 2 to precipitate if these two compounds were present in the same solution with the sodium hydroxide, those ingredients of the dishwashing medium 14 which are incompatible in concentrated solutions are first formed into separate concentrated wash solutions. Additionally, the ethyloxylated fatty alcohol or polyethyloxylated fatty alcohol and sodium xylenesulfonate of solution 3, when present in concentrated solutions, cannot be mixed with solution 2 since the latter would cause separation of the organic portion of solution 3. Similarly, the ingredients of the rinse additive cannot be mixed in concentrated solution with solution 1 since the hypochlorite therein would decompose the organic constituents. Hence, the rinsing ingredients must likewise be formed into a concentrated rinsing solution separate from the washsolutions. With the valve 34 closed and the valve 28 open, water passing through the conduit 26 causes a rise in pressure in the tapline 54 to which the pressure switch 52 is responsive to commence the flow of solutions 1, 2 and 3 respectively. When the flow of water past the valve 28 ceases, the pressure switch 52 senses the decrease in pressure in conduit 26 and in response thereto deenergizes the pumps 40, 46 and 50 to stop the flow of the wash and rinse solutions 1, 2 and 3. It will be appreciated that the check valve 60 is necessary for establishing an increase in pressure in the tapline 54. Since check valve 62 is present in arm 58, this latter check valve must be of the imperfect seating type to allow sufficient leakage of water past it to deactivate the pressure switch 52 when the flow of water through the conduit 26 ceases.

The foregoing described situation, namely, with the valve 28 open and the valve 34 closed normally exists only during the initial filling of the machine and once this has been accomplished, the valve 28 is closed and the machine motors (not shown) are actuated to commence the washing cycle.

The valve 34 is under the control of the solenoid 36 and as the washing cycle progresses, the wash medium 14 is diluted by the periodic addition of water thereto as a result of water passing through the rinse line 30 in response to opening of the valve 34. As water passes through the line 30 the first arm 56 and the tapline 54 direct the water to the pressure switch 52 which senses the increase in pressure resulting from the addition of rinse water and in response thereto commences the flow of rinse solution 3 into the rinse line 30 while at the same time commencing the flow of wash solutions 1 and 2 into the washing medium 14. Because the pressure regulator 38 assures a constant pressure in the line 30 regardless of variations in pressure within limits in the supply line, the pressure switch 52 is actuated during the period of timer operation to assure that a predetermined quantity of each of solutions Nos. 1, 2 and 3, is added to the washing medium 14 in proportion to the quantity of rinse water being added thereto.

it is to be noted that check valve 62 is necessary for establishing pressure in the tapline 54 and, as is the case with check valve 62, check valve 60 must be of the imperfect seating type to assure sufficient leakage of water therepast to deactuate the pressure switch when the flow of rinse water through the line 30 ceases. The decrease in pressure in the rinse line 30 is sensed by the switch 52 which then deenergizes the pumps 40, 46 and 50 to stop the flow of the washing and rinse solutions into the medium 14 and the rinse line 50, respectively.

It will be appreciated that by the foregoing method all sensory mechanism in the dishwashing medium 14 is eliminated and a predetermined quantity of each of the active ingredients of the dishwashing medium, as well as the rinse additive, are added each time water-is added to the machine 10. It is to be noted that the washing solutions 1 and 2 are introduced into the machine 10 at a point below the wash rack support 20 so as not to get soap on freshly washed dishes during the rinse cycle. When the pumps 40, 46 and 50 are of the squeegee type, as is preferred, the size of the flexible conduit in the pump can be varied to vary the quantity of each solution being added for any given quantity of water being introduced into the machine.

While the method of the present invention has been described with reference to a washing medium comprised of sodium hydroxide, sodium hypochlorite, sodium tripolyphosphate and sodium hexaphosphate, it is to be understood that any alkali metal hydroxide, including sodium hydroxide and potassium hydroxide as well as any alkali metal hypochlorite, including sodium hypochlorite and potassium hypochlorite could be dissolved in a solvent therefor to present solution No. 1. Other complex inorganic salts which may be substituted for the sodium hexaphosphate and sodium tripolyphosphate mentioned in the preferred embodiment include sodium tetraphosphate, (tetra) sodium pyrophosphate, potassium tetraphosphate, and (tetra) potassium pyrophosphate. In general, any sodium or potassium complex phosphate may be utilized. The term complex phosphate is meant to include any sodium or potassium phosphate salt which is capable of forming a complex ion with other metals in solution. In certain instances it is desirable to substitute a sodiurn or potassium phosphate, salt plus an organic chelating agent for the complex phosphate. An alternative formation of solution 2 is 59 pounds of sodium tripolyphosphate, added slowly to 50 gallons of water at 60 F., 50 pounds of sodium hexametaphosphate, and 23 pounds of the sodium salt of nitrilotriacetic acid, with the final solution being diluted to 70 gallons. As previously mentioned, however, it is necessary to maintain solutions I and 2 separate because the hypochlorite of solution 1 will destroy the organic molecules in solution 2. Also, solutions I and 3 must be maintained separate for the reasons previously discussed. Hence, the incompatible ingredients are first formed into separated concentrated washing and rinsing solutions and then introduced into the machine 10 as previously discussed. Other examples of organic chelating agents which can be utilized include triethylenetetramine and diethylenetriaminepentacetic acid.

It should also be emphasized that while in the preferred example one of the ingredients of the washing medium was described as comprising two compatible compounds dissolved in a solvent therefor and the other of the ingredients was described as including three compatible compounds dissolved in a solvent therefor, the present invention is directed to a method of introducing two incompatible ingredients into a dishwashing medium and in certain instances each of the ingredients may comprise only a single compound dissolved in a solvent therefor. On the other hand, it may be desirable to have more than two active ingredients in the dishwashing medium and in such case the principles of the present invention can be extended to cover the introduction of more than two incompatible ingredients into a single medium.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

l. A method of adding active ingredients to a liquid dishwashing medium as the latter becomes diluted by addition of water thereto, wherein the ingredients are incompatible in concentrated solutions, said method comprising the steps of:

forming the ingredients into separate concentrated solutions;

adding water to the dishwashing medium;

sensing addition of said water to the medium; and

independently and simultaneously introducing a quantity of each of said solutions into said medium each time water is added thereto in response to sensing of said water addition and in predetermined relative proportions with respect to the quantity of the water being added, said solutions being maintained out of contacting relationship prior to introduction thereof into the dishwashing medium.

2. A method as set forth in claim l, wherein said step of forming the ingredients into separate concentrated solutions includes forming a first solution by adding a first compound selected from the group consisting of the alkali metal hydroxides and a second compound selected from the group consisting of the alkali metal hypochlorites to a solvent therefor, and forming a second solution by adding a third compound selected from the group consisting of A and it, where A is selected from the group consisting of sodium and potassium complex phosphates and B is an organic chelating agent plus a member selected from the group consisting of sodium or potassium phosphate, to a solvent therefor.

3. A method as set forth in claim ll wherein water under pressure is added to the dishwashing medium and said step of introducing said solutions into the medium includes sensing passage of additional water to the dishwashing medium, and continuing introduction of said solutions to the dishwashing medium throughout the period of water addition thereto.

l. A method for washing and rinsing dishes in a commercial dishwashing machine wherein a liquid dishwashing medium is diluted by periodic addition of water thereto and a liquid rinse additive is periodically introduced into the rinse line in pro portion to the quantity of water added to the medium, said dishwashing medium being comprised of washing ingredients which are incompatible in concentrated solutions and said rinse additive being comprised of a rinsing ingredient which is incompatible in concentrated solution with one of said washing ingredients in concentrated solution, said method comprising the steps of:

forming the washing ingredients into separate concentrated wash solutions;

forming the rinsing ingredient into a concentrated rinsing solution separate from said wash solutions;

independently introducing a quantity of each of said wash ing solutions directly into said medium each time water is added thereto in response to water addition and in predetermined relative proportions with respect to the quantity of water being added;

detecting the flow of rinse water through said line by sensing the increase in pressure therein; and

providing a uniform flow of said rinse solution into the line independently of said washing solutions and in response to said detection of the increase in pressure of water passing therethrough.

1'5. A method as set forth in claim d, wherein the periodic addition of water to the dishwashing medium results from the periodic passing of water through said rinse lines, said step of independently introducing a quantity of each of said washing solutions includes commencing the flow of each of said washing solutions into the dishwashing medium in response to said sensing of the pressure in the rinse line.

(ii. A method as set forth in claim 5, wherein is included the steps of sensing the decrease in pressure in the line when the flow of water therethrough ceases and stopping the flow of said washing and rinse solutions into said medium and said rinse line, respectively, in response to said sensing the decrease in ressure.

'7. A me od as set forth m claim 4, wherein said step of forming the washing ingredients into separate concentrated solutions includes forming a first solution by adding a first compound selected from the group consisting of the alkali metal hydroxides and a second compound selected from the group consisting of the alkali metal hypochlorites to a solvent therefor, and forming a second solution by adding a third compound selected from the group consisting of A and B, where A is selected from the group consisting of sodium and potassium complex phosphates and l8 is a sodium or potassium phosphate plus an organic chelating agent, to a solvent therefor, and said step of forming the rinsing ingredient into a concentrated rinse solution includes adding a quantity of an ethyloxylated fatty alcohol, sodium rrylcnesulionate and isopropylalcohol to a solvent therefor. 

1. A method of adding active ingredients to a liquid dishwashing medium as the latter becomes diluted by addition of water thereto, wherein the ingredients are incompatible in concentrated solutions, said method comprising the steps of: forming the ingredients into separate concentrated solutions; adding water to the dishwashing medium; sensing addition of said water to the medium; and independently and simultaneously introducing a quantity of each of said solutions into said medium each time water is added thereto in response to sensing of said water addition and in predetermined relative proportions with respect to the quantity of the water being added, said solutions being maintained out of contacting relationship prior to introduction thereof into the dishwashing medium.
 2. A method as set forth in claim 1, wherein said step of forming the ingredients into separate concentrated solutions includes forming a first solution by adding a first compound selected from the group consisting of the alkali metal hydroxides and a second compound selected from the group consisting of the alkali metal hypochlorites to a solvent therefor, and forming a second solution by adding a third compound selected from the group consisting of A and B, where A is selected from the group consisting of sodium and potassium complex phosphates and B is an organic chelating agent plus a member selected from the group consisting of sodium or potassium phosphate, to a solvent therefor.
 3. A method as set forth in claim 1 wherein water under pressure is added to the dishwashing medium and said step of introducing said solutions into the medium includes sensing passage of additional water to the dishwashing medium, and continuing introductiOn of said solutions to the dishwashing medium throughout the period of water addition thereto.
 4. A method for washing and rinsing dishes in a commercial dishwashing machine wherein a liquid dishwashing medium is diluted by periodic addition of water thereto and a liquid rinse additive is periodically introduced into the rinse line in proportion to the quantity of water added to the medium, said dishwashing medium being comprised of washing ingredients which are incompatible in concentrated solutions and said rinse additive being comprised of a rinsing ingredient which is incompatible in concentrated solution with one of said washing ingredients in concentrated solution, said method comprising the steps of: forming the washing ingredients into separate concentrated wash solutions; forming the rinsing ingredient into a concentrated rinsing solution separate from said wash solutions; independently introducing a quantity of each of said washing solutions directly into said medium each time water is added thereto in response to water addition and in predetermined relative proportions with respect to the quantity of water being added; detecting the flow of rinse water through said line by sensing the increase in pressure therein; and providing a uniform flow of said rinse solution into the line independently of said washing solutions and in response to said detection of the increase in pressure of water passing therethrough.
 5. A method as set forth in claim 4, wherein the periodic addition of water to the dishwashing medium results from the periodic passing of water through said rinse lines, said step of independently introducing a quantity of each of said washing solutions includes commencing the flow of each of said washing solutions into the dishwashing medium in response to said sensing of the pressure in the rinse line.
 6. A method as set forth in claim 5, wherein is included the steps of sensing the decrease in pressure in the line when the flow of water therethrough ceases and stopping the flow of said washing and rinse solutions into said medium and said rinse line, respectively, in response to said sensing the decrease in pressure.
 7. A method as set forth in claim 4, wherein said step of forming the washing ingredients into separate concentrated solutions includes forming a first solution by adding a first compound selected from the group consisting of the alkali metal hydroxides and a second compound selected from the group consisting of the alkali metal hypochlorites to a solvent therefor, and forming a second solution by adding a third compound selected from the group consisting of A and B, where A is selected from the group consisting of sodium and potassium complex phosphates and B is a sodium or potassium phosphate plus an organic chelating agent, to a solvent therefor, and said step of forming the rinsing ingredient into a concentrated rinse solution includes adding a quantity of an ethyloxylated fatty alcohol, sodium xylenesulfonate and isopropylalcohol to a solvent therefor. 